Systematic interpretation of differential capacitance data

Nir Gavish and Keith Promislow
Phys. Rev. E 92, 012321 – Published 23 July 2015

Abstract

Differential capacitance (DC) data have been widely used to characterize the structure of electrolyte solutions near charged interfaces and as experimental validation of models for electrolyte structure. Fixing a large class of models of electrolyte free energy that incorporate finite-volume effects, a reduction is identified which permits the identification of all free energies within that class that return identical DC data. The result is an interpretation of DC data through the equivalence classes of nonideality terms, and associated boundary layer structures, that cannot be differentiated by DC data. Specifically, for binary salts, DC data, even if measured over a range of ionic concentrations, are unable to distinguish among models which exhibit charge asymmetry, charge reversal, and even ion crowding. The reduction applies to capacitors which are much wider than the associated Debye length and to finite-volume terms that are algebraic in charge density. However, within these restrictions the free energy is shown to be uniquely identified if the DC data are supplemented with measurements of the excess chemical potential of the system in the bulk state.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
4 More
  • Received 21 May 2015

DOI:https://doi.org/10.1103/PhysRevE.92.012321

©2015 American Physical Society

Authors & Affiliations

Nir Gavish*

  • Department of Mathematics, Technion — Israeli Institute of Technology, Haifa 3200003, Israel

Keith Promislow

  • Department of Mathematics, Michigan State University, East Lansing, Michigan 48824, USA

  • *ngavish@tx.technion.ac.il
  • kpromisl@math.msu.edu

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 92, Iss. 1 — July 2015

Reuse & Permissions
Access Options
CHORUS

Article Available via CHORUS

Download Accepted Manuscript
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review E

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×